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Allow fix python to only execute every N steps

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This commit is contained in:
Richard Berger
2017-05-12 00:29:58 -04:00
parent 93f6033061
commit c4d0f07093
3 changed files with 18 additions and 12 deletions
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13
doc/src/fix_python.txt
View File

@ -10,13 +10,14 @@ fix python command :h3
[Syntax:]
fix ID group-ID python callback function_name :pre
fix ID group-ID python N callback function_name :pre
ID, group-ID are ignored by this fix :ulb,l
python = style name of this fix command :l
N = execute every N steps :l
callback = {post_force} or {end_of_step} :l
{post_force} = callback after force computations on atoms
{end_of_step} = callback after each time step :pre
{post_force} = callback after force computations on atoms every N time steps
{end_of_step} = callback after each N time steps :pre
:ule
[Examples:]
@ -35,14 +36,14 @@ def end_of_step_callback(lammps_ptr):
# access LAMMPS state using Python interface
""" :pre
fix pf all python post_force post_force_callback
fix eos all python end_of_step end_of_step_callback :pre
fix pf all python 50 post_force post_force_callback
fix eos all python 50 end_of_step end_of_step_callback :pre
[Description:]
This fix allows you to call a Python function during a simulation run.
The callback is either executed after forces have been applied to atoms
or at the end of each time step.
or at the end of every N time steps.
Callback functions must be declared in the global scope of the
active Python interpreter. This can either be done by defining it

4
examples/python/in.fix_python
View File

@ -33,8 +33,8 @@ def post_force_callback(lmp, v):
"""
fix 1 all nve
fix 2 all python end_of_step end_of_step_callback
fix 3 all python post_force post_force_callback
fix 2 all python 50 end_of_step end_of_step_callback
fix 3 all python 50 post_force post_force_callback
#dump id all atom 50 dump.melt

13
src/PYTHON/fix_python.cpp
View File

@ -36,14 +36,17 @@ using namespace FixConst;
FixPython::FixPython(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg)
{
if (narg != 5) error->all(FLERR,"Illegal fix python command");
if (narg != 6) error->all(FLERR,"Illegal fix python command");
nevery = force->inumeric(FLERR,arg[3]);
if (nevery <= 0) error->all(FLERR,"Illegal fix python command");
// ensure Python interpreter is initialized
python->init();
if (strcmp(arg[3],"post_force") == 0) {
if (strcmp(arg[4],"post_force") == 0) {
selected_callback = POST_FORCE;
} else if (strcmp(arg[3],"end_of_step") == 0) {
} else if (strcmp(arg[4],"end_of_step") == 0) {
selected_callback = END_OF_STEP;
}
@ -57,7 +60,7 @@ FixPython::FixPython(LAMMPS *lmp, int narg, char **arg) :
error->all(FLERR,"Could not initialize embedded Python");
}
char * fname = arg[4];
char * fname = arg[5];
pFunc = PyObject_GetAttrString(pyMain, fname);
if (!pFunc) {
@ -94,6 +97,8 @@ void FixPython::end_of_step()
void FixPython::post_force(int vflag)
{
if (update->ntimestep % nevery != 0) return;
PyGILState_STATE gstate = PyGILState_Ensure();
PyObject * ptr = PY_VOID_POINTER(lmp);